Sökning: "Galaxy: halo"

Visar resultat 16 - 20 av 21 avhandlingar innehållade orden Galaxy: halo.

  1. 16. Spectral Analysis of Neutron Capture Elements in the Laboratory and Stars

    Författare :Martin Lundqvist; Astronomi - Genomgår omorganisation; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; cosmic chemistry; Astronomy; space research; Atom- och molekylärfysik; Atomic and molecular physics; Astronomi; Sm; Hf; Os; Ir; Neutron capture processes; rymdvetenskap; kosmisk kemi; cool stars; Spectroscopy; atomic data;

    Sammanfattning : The pedigree of the elements heavier than iron is a vital question in the history and evolution of our galaxy. The elements up to and including those of the iron group are produced mainly through fusion processes within stars, giving the stars their energy. LÄS MER

  3. 17. Transport, Turbulence and Instabilities in Cosmic Magnetic Fields

    Författare :Giuseppe Di Bernardo; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cosmic Rays; Interstella Medium; Galactic Magnetic Fields; Magnetohydrodynamics Turbulence; Accretion Discs;

    Sammanfattning : This decade has seen a large number of space missions, which, alongside ground-based radio, optical and gamma-ray telescopes, have enabled a deep insight into the non-thermal astrophysical environments. Interstellar Medium (ISM), Supernovae Remnants (SNRs) and Black-Hole (BH) accretion discs (ADs) are only a few examples of natural habitat of interaction of relativistic particles and magnetic fields, largely mediated by the action of the turbulence. LÄS MER

  4. 18. Dwarf and Subgiant Stars as Probes of Galactic Chemical and Dynamical Evolution

    Författare :Patrik Thorén; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; Abundances; atomic data; Galactic evolution; late-type stars; main sequence stars; subgiants; Pop II; Pop I; stellar evolution; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik; astronomi; Astronomy;

    Sammanfattning : Stellar chemical abundances provide astronomers with vital information about the production of chemical elements. Some stars preserve the composition of the environment in which they were born on their surfaces. LÄS MER

  5. 19. How ISM properties drive Lyman Continuum Escape

    Författare :Johannes Puschnig; Matthew Hayes; Göran Östlin; Rahman Amanullah; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astrophysics; Cosmology; Extragalactics; Reionization; Lyman Continuum; Interstellar Medium; ISM; Tololo 1247-232; Astronomy; astronomi;

    Sammanfattning : The thesis introduces physical processes that are at work in astrophysical plasmas and reviews the current state of research related to the emission of ionizing photons, i.e. Lyman continuum (LyC). Star forming galaxies and active galactic nuclei are discussed as sources of LyC. LÄS MER

  7. 20. Stochastic Chemical Evolution : A Study of Scatter in Relative Elemental Abundances in Extremely Metal-poor Stars

    Författare :Torgny Karlsson; Bengt Gustafsson; Mike Edmunds; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; nucleosynthesis; chemical evolution; Galactic evolution; supernovae; chemical abundances; Population II stars; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik;

    Sammanfattning : Chemical evolution addresses the problem of the formation of the chemical elements and their evolution throughout the history of the universe. This thesis discusses in particular the chemical evolution in the young universe and what we may learn from the observations of the oldest stars. LÄS MER